Why am I magnetic?

When ever I go into Barns & Nobles, Ulta Salons or any Walgreens, I set off their detectors. On the way in and the way out.

I have experimented with have absolutely no metal on me and just wearing sweats and sandals - no metal. I don't have any glasses, no watch, no keys, no wallet, no pacemaker, no static in my hair, only a few very old fillings in my teeth, no pins in bones, nothing that I can think of.

Even with my keys and phone and regular jeans and tennis shoes I never set off any other stores' alarms - just these three, everytime, no matter what I'm carrying or not carrying.

Maybe you're just real suspicious-looking and store security triggers the alarms when they see you in the security cameras to subject you to a bit of extra "attention". Do you wear really baggy clothing or carry large bags with you? If so, you will attract attention as a risk of theft. Just because an alarm at a store goes off, it does not mean that you have triggered a sensor. There is a lot of human intervention behind the scenes in chain stores.

No - I look normal and it happens no matter what I wear and I'm never carrying anything. It's not a human triggered alarm - It's the same beeper that goes off when people try to steal stuff as they leave the store. Those devices that you walk through detect whether the sale tag has been demagnetized or not. They sense magnetism and they are automatic.

Hmmm, IIRC some of these detectors work on detecting a load on their oscillator tank circuit.
In some cases dental fillings (particularly old fillings) have been known to pick up radio stations.
In your case one of your fillings might be the culprit.

This may be a long shot, but is it possible that you got one of those little sticky magnetic tags stuck to something you're carrying, like a backpack or your shoes? How long ago did you first start setting off the alarms?

This may be a long shot, but is it possible that you got one of those little sticky magnetic tags stuck to something you're carrying, like a backpack or your shoes? How long ago did you first start setting off the alarms?

You may have it. Some products actually have those hidden internally (maybe in a seam) and the store clerks don't know exactly where so they can't demag them fully.